Various different types of window coverings are available, such as vertical slats, venetians, concertina, panels of various fabrics, russians, balloons and others. These window coverings almost universally incorporate a head rail of some kind which can be attached above or adjacent to a window or doorway or building opening. The window covering can then be either lowered down and raised, or can be drawn from one side across the window and back again.
These window coverings in the past have been designed around various different head rail structures specific to that type of window covering. For a manufacturer to provide a full range of window coverings, each one of which required a specially designed head rail, was a considerable investment. It also meant that the manufacturer would be obliged to carry an inventory of numerous different parts for numerous different head rails.
In addition to these considerations, in the marketing of window coverings, customers are often uncertain as to which type of particular window covering will suit their needs. For example, if a customer orders window coverings with vertical slats and then decides for example that they would prefer a pleated panel of material, then the supplier would be obliged to remove the window covering completely and replace it with a different one and a different head rail. This would also result in many cases, damage to the building structure around the opening. Even though such damage might be slight, such as for example the requirements for inserting different fastenings in different positions for different window coverings, the completion of the work would require at least the covering of the previous fastening openings in the building, before the new or replacement window covering could be attached.
Finally, in the event of a window covering becoming unserviceable or requiring some kind of repair, it will be preferable if instead of repairing an existing window covering, the portion which is unserviceable can simply be replaced, without the need for removing the entire head rail and replacing it with a new window covering.
For any of these reasons, it is desirable to provide a head rail which removably supports a separate window covering support, and which can be readily adapted to support a variety of different types of window coverings, with a minimum of adaptation. Preferably the head rail incorporates parts which are interchangeable.